The present invention relates generally to holographic lighting devices, and more particularly, to a holographic stop light for use in vehicular applications.
Every time a school bus comes to a stop and lets out child pedestrians, there is a potential for tragic fatal accidents between oncoming traffic and the child pedestrians. Last year alone, a large number of children in the United States were killed by vehicles passing by school buses.
Therefore, there is a great need in school buses to display a warning to oncoming vehicles that the bus is at a stop and the approaching vehicle should stop also. Prior art apparatus for providing "STOP" warning in school buses, for example, include mechanical "STOP" arms that move down when the driver comes to a stop. The mechanical arm is visible during the day but not very visible at night. Another apparatus is the use of flashing red warning lights on the bus to indicate the bus is stopped.
Unfortunately, studies have shown that neither of these methods is fully effective at catching the attention of oncoming vehicles. Studies have shown that a certain percentage of oncoming vehicles pass the stopped bus in spite of the warning indicator. Some of these drivers did see the warning but chose to ignore it; however, a significant percentage of these drivers simply did not see the warning indicator, perhaps because they were preoccupied or not looking directly at the bus. Therefore the conclusion that some fatal bus-related accidents occur because the driver of the oncoming vehicle did not see the "STOP" warning is inescapable.
Therefore, there is a need for a new warning indicator for use by school buses that is more conspicuous and captures the attention of a greater number of oncoming vehicles.
One prior art holographic lighting device that is particularly related to the present invention is described in U.S. Pat. No. 4,916,593 entitled "Remotely Illuminated Transparent Holographic Stoplight for Automobiles", assigned to the assignee of the present invention. U.S. Pat. No. 4,916,593 is discloses a holographic center-mounted, high-mounted, stop lamp located in a rear window of a vehicle that is horizontally centered on the rear window. A laterally symmetric field of view is generated by the diffracted light produced by this holographic stop lamp. The present invention does not have these limitations. The holographic center mounted stop lamp of U.S. Pat. No. 4,916,593 does not flash and uses only one lamp, and is only on when the driver applies the brakes. The present invention improves upon the teachings of U.S. Pat. No. 4,916,593.
Accordingly, it is an objective of the present invention to provide for an improved warning indicator for use by school buses and other vehicles. It is a further objective of the present invention to provide for an improved warning indicator that employs a holographic device as the indicator.